can not find toDataStresam in DataSet in apache flink

The correct method name is writeAsText() instead of toDataStream() in Apache Flink's DataSet API. This method writes the DataSet to a text file or a text stream.

Example usage:

DataSet<String> input = env.fromElements("hello", "world");
input.writeAsText("output.txt");

This will write the contents of the DataSet to a text file named "output.txt".

Alternatively, you can also use print() method to print the contents of the DataSet to the console:

DataSet<String> input = env.fromElements("hello", "world");
input.print();

This will print the contents of the DataSet to the console.